Reinforcement of Stereolithographic Resins for Rapid Prototyping with Cellulose Nanocrystals

Abstract

We report on the mechanical properties of optically curable stereolithographic resins (SLRs) which were reinforced through the addition of small amounts of cellulose nanocrystals (CNCs). The resin/filler mixtures are readily accessible via simple mixing processes. A detailed rheological investigation of such mixtures and the successful processing of these materials on a commercial SLR machine show that at low filler concentrations (below 5%) the processability of the materials is barely impacted. The storage modulus, E', increased steadily with increasing CNC content in the regimes below and above the glass transition. A remarkable modulus enhancement was observed in the rubbery regime, where E' increased by 166, 233, and 587% for CNC/SLR nanocomposites with 0.5, 1.0, and 5.0% w/w CNC, respectively. The modulus increase was less pronounced in the glassy state, where E' increased by 21, 32 and 57%, for the same compositions. The increase in tensile strength was of similar magnitude. In comparison to previously reported CNC and carbon-nanofiller based nanocomposites, the presently investigated nanocomposites display a comparably large increase of stiffness and strength, which appear to originate from the high level of dispersion and the intimate contact of the CNCs with the SLR matrix. Through the fabrication of 3-dimensional parts, it was shown that the CNC-filled resins can be processed with standard equipment in a stereolithographic process that is widely used for rapid prototyping and rapid manufacturing.

Additive Manufacturing of Cellulosic Materials with Robust Mechanics and Antimicrobial Functionality

“…However, because of its strong hydrogen bonding, pure cellulose degrades upon heating before becoming sufficiently flowable for extrusion-based AM. [6] As a result, extant methods of AM using cellulose-containing feedstock have used low cellulose concentrations, either as a filler in other materials [7,8] or in solvent/ suspension. [9,10] For example, cellulose nanocrystals have been incorporated into polymers for additive manufacturing, [7,8] but the low cellulose concentration combined with the general difficulties of bonding cellulose to polymers result in only small wileyonlinelibrary.com not compromise the 3D printed part quality.…”

Možnosti uporabe lesa v dodajalnih tehnologijah (3D-tiskanju)

“…Še bolj obetajoča je uporaba nanoceluloze kot ojačitvenega dodatka k že znanim tehnikam in materialom. Kumar et al, (2012) so že s primešanim 5 % dodatkom celuloznih nanokristalov optično utrjujočim smolam za stereolitografijo dosegli izboljšanje modula elastičnosti in natezne trdnosti v trdnem stanju za 57 %, ne da bi vplivali na sam način uporabe smole. 30 % dodatek nanoceluloznih fibril je tako za 3,6-krat izboljšal modul elastičnosti PLA materiala, ki se veliko uporablja v FDM tehniki tiskanja (Žepič et al, 2016), tiskanje pa je mogoče tudi s nanoceluloznimi hidrogeli (Pinomaa 2016;Leppiniemi et al, 2017).…”

3D Printing Fabrication of Amorphous Thermoelectric Materials with Ultralow Thermal Conductivity

“…[ 2 ] The principle of this technology relates to building up the objects by optically curing liquid photoresins during the layer-by-layer printing processes. [ 3,4 ] The 3D printing of photoresins, which exhibits the advantages of cost-effective utilization, high building accuracy, and fast fabrication, has been widely applied to rapid prototyping and manufacturing. [5][6][7] In the past several years, there has been considerable interest in the application of 3D printing technologies for creating bionic ear, [ 8 ] "reactionware" for chemical science, [ 9,10 ] fl ow plates for water electrolysis, [ 11 ] lithium-ion microbattery, [ 12 ] bone scaffolds, [ 13 ] multifunctional microsystems, [ 14 ] cell-laden tissue constructs, [ 15 ] lightweight cellular composites, [ 16 ] and so on.…”